truck is stock i make sure the air filter is clean and the right tire pressure , maybe its the 10% enthenol in the gas, i bought the truck with 105,000 miles and its been getting about 11mpg going to work everyday.

Sclam! I love my 4.8L, whats up with the 10% ethanol in your tank? how much $ do you save by adding 10% ehanol. Does adding ethanol have any side effects on the engine?

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In California its 10% ethanol in the gas. I dont think it runs as well but were gonna save the world here in Cali (sarcasm):rofl:.

When my 2500 6.0 was newer I could get close to 13 almost all highway, even hit 15 on an a 600 mile highway trip to northern california, but have always averaged in the 11-12 range mostly highway. aint nothing you can really do to increase mileage. its a brick. I have magnaflow exhaust, airraid intake and tbs but didnt notice any improvements. when I lifted my truck I went to 4.10's instead of 4.56 since I do about 85% highway on my commute so the rpms were lower than stock on highway, but had to sacrifice some get up and go. this allowed me to maintain the same mileage from when it was stock. Basically I drive like a grandma most of the time in it. 65 on the highway and a stay out of the throttle (gotta punch it every now and then though:lol. when doing mostly highway like this I will still get between 11-12 mpg. when I have to do more city driving it obviously drops. In the end sounds like your mileage is right on and there aint much you can do about it.

11mpg isn't bad if your trip to work is partially city/suburban.
The EPA claims that 105 ethanol should only drop mpg by 3%,
But I'm a member of a MPG forum, and the folks there despise ethanol gas and claim it drops their MPG by 5-10%.
I'm pretty sure it has dropped my Prius mpg from 42 down to 40 or less- 5% or more.
P&G pulse and glide- gets me about 16mpg in city driving-once it is warmed up. Actual tank mpg is about 13 mpg in my 1998 Suburban- in pure city short trip driving.(4 miles one way).
Try pulse and gliding
Charlie

i have a 2003 2500 6.0. i was wondering if anyone got better then the 11mpg i'm currently getting and how you did it, how much mpg did you gain, and what did it cost?

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I sure hope you are not getting 11mpg with a 6.0 on the hiway! My 07 suburban 2500 with the 6.0 gets atleast 18.5 to 20 on the hiway and in city i avg.
13.9 and up. I keep my fooy out of it and drive no faster than 64 mph and have my Edge CS set at level 2 Economy. I have gotten 20 mpg on a decent trip.

I sure hope you are not getting 11mpg with a 6.0 on the hiway! My 07 suburban 2500 with the 6.0 gets atleast 18.5 to 20 on the hiway and in city i avg.
13.9 and up. I keep my fooy out of it and drive no faster than 64 mph and have my Edge CS set at level 2 Economy. I have gotten 20 mpg on a decent trip.

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i get better mpg on the highway but back and forth to work everyday is hills and city and i've been getting about 11.3 mpg. i wasn't sure if putting a catback exhaust or a cold air intake would help much